[1] S. Ohno, Q. Li, N. Sekine, H. Tang, S. Monfray, F. Boeuf, K. Toprasertpong, S. Takagi, M. Takenaka. Si microring resonator optical switch based on optical phase shifter with ultrathin-InP/Si hybrid metal-oxide-semiconductor capacitor. Opt. Express, 29, 18502-18511(2021).

[2] P. Dong, W. Qian, H. Liang, R. Shafiiha, N.-N. Feng, D. Feng, X. Zheng, A. V. Krishnamoorthy, M. Asghari. Low Power and compact reconfigurable multiplexing devices based on silicon microring resonators. Opt. Express, 18, 9852-9858(2010).

[3] W. D. Sacher, J. K. Poon. Dynamics of microring resonator modulators. Opt. Express, 16, 15741-15753(2008).

[4] Y. Yuan, W. V. Sorin, Z. Huang, X. Zeng, D. Liang, A. Kumar, S. Palermo, M. Fiorentino, R. G. Beausoleil. A 100  GB/s PAM4 two-segment silicon microring resonator modulator using a standard foundry process. ACS Photon., 9, 1165-1171(2022).

[5] K. De Vos, I. Bartolozzi, E. Schacht, P. Bienstman, R. Baets. Silicon-on-insulator microring resonator for sensitive and label-free biosensing. Opt. Express, 15, 7610-7615(2007).

[6] S. N. Zheng, J. Zou, H. Cai, J. F. Song, L. K. Chin, P. Y. Liu, Z. P. Lin, D. L. Kwong, A. Q. Liu. Microring resonator-assisted Fourier transform spectrometer with enhanced resolution and large bandwidth in single chip solution. Nat. Commun., 10, 2349(2019).

[7] M. Bahadori, Y. Yang, A. E. Hassanien, L. L. Goddard, S. Gong. Ultra-efficient and fully isotropic monolithic microring modulators in a thin-film lithium niobate photonics platform. Opt. Express, 28, 29644-29661(2020).

[8] K. Y. Yang, D. Y. Oh, S. H. Lee, Q.-F. Yang, X. Yi, B. Shen, H. Wang, K. Vahala. Bridging ultrahigh-Q devices and photonic circuits. Nat. Photonics, 12, 297-302(2018).

[9] M. W. Puckett, K. Liu, N. Chauhan, Q. Zhao, N. Jin, H. Cheng, J. Wu, R. O. Behunin, P. T. Rakich, K. D. Nelson, D. J. Blumenthal. 422 million intrinsic quality factor planar integrated all-waveguide resonator with sub-MHz linewidth. Nat. Commun., 12, 934(2021).

[10] J. Liu, J. Du, W. Shen, G. Zhou, L. Zhou, W. Zhang, K. Xu, Z. He. Ultrahigh extinction ratio silicon micro-ring modulator by MDM resonance for high speed PAM-4 and PAM-8 signaling. Opt. Express, 30, 25672-25684(2022).

[11] L. Zhou, L. Lu, S. Zhao, D. Li, Z. Guo, J. Chen. Silicon active microring resonators for optical switching. 2016 Progress in Electromagnetic Research Symposium (PIERS), 2621(2016).

[12] H. Zhu, I. M. White, J. D. Suter, P. S. Dale, X. Fan. Analysis of biomolecule detection with optofluidic ring resonator sensors. Opt. Express, 15, 9139-9146(2007).

[13] X. Ou, Y. Yang, F. Sun, P. Zhang, B. Tang, B. Li, R. Liu, D. Liu, Z. Li. Wide-range, ultra-compact, and high-sensitivity ring resonator biochemical sensor with CMOS-compatible hybrid plasmonic waveguide. Opt. Express, 29, 19058-19067(2021).

[14] B. Hinkov, F. Pilat, L. Lux, P. L. Souza, M. David, A. Schwaighofer, D. Ristanić, B. Schwarz, H. Detz, A. M. Andrews, B. Lendl, G. Strasser. A mid-infrared lab-on-a-chip for dynamic reaction monitoring. Nat. Commun., 13, 4753(2022).

[15] M. Sieger, B. Mizaikoff. Toward on-chip mid-infrared sensors. Anal. Chem., 88, 5562-5573(2016).

[16] U. Willer, M. Saraji, A. Khorsandi, P. Geiser, W. Schade. Near- and mid-infrared laser monitoring of industrial processes, environment and security applications. Opt. Laser Eng., 44, 699-710(2006).

[17] C. Daffara, S. Parisotto, P. I. Mariotti, D. Ambrosini. Dual mode imaging in mid infrared with thermal signal reconstruction for innovative diagnostics of the ‘Monocromo’ by Leonardo da Vinci. Sci. Rep., 11, 22482(2021).

[18] P. Werle, R. Mücke, F. Slemr. The limits of signal averaging in atmospheric trace-gas monitoring by tunable diode-laser absorption spectroscopy (TDLAS). Appl. Phys. B, 57, 131-139(1993).

[19] A. Dabrowska, A. Schwaighofer, S. Lindner, B. Lendl. Mid-IR refractive index sensor for detecting proteins employing an external cavity quantum cascade laser-based Mach-Zehnder interferometer. Opt. Express, 28, 36632-36642(2020).

[20] H. Lin, Z. Luo, T. Gu, L. C. Kimerling, K. Wada, A. Agarwal, J. Hu. Mid-infrared integrated photonics on silicon: a perspective. Nanophotonics, 7, 393-420(2017).

[21] A. Malik, M. Muneeb, S. Pathak, Y. Shimura, J. Van Campenhout, R. Loo, G. Roelkens. Germanium-on-silicon mid-infrared arrayed waveguide grating multiplexers. IEEE Photon. Technol. Lett., 25, 1805-1808(2013).

[22] Q. Liu, J. M. Ramirez, V. Vakarin, J. Frigerio, A. Ballabio, L. Vivien, C. Alonso-Ramos, G. Isella, D. Marris-Morini. Mid-IR integrated cavity based on Ge-rich graded SiGe waveguides with lateral Bragg grating. Mid-Infrared Coherent Sources 2018, MM3C.4(2018).

[23] L. Zhang, A. M. Agarwal, L. C. Kimerling, J. Michel. Nonlinear Group IV photonics based on silicon and germanium: from near-infrared to mid-infrared. Nanophotonics, 3, 247-268(2014).

[24] Z. Zhao, C.-M. Lim, C. Ho, K. Sumita, Y. Miyatake, K. Toprasertpong, S. Takagi, M. Takenaka. Low-loss Ge waveguide at the 2-μm band on an N-type Ge-on-insulator wafer. Opt. Mater. Express, 11, 4097-4106(2021).

[25] K. Gallacher, R. W. Millar, U. Griškevičiūte, L. Baldassarre, M. Sorel, M. Ortolani, D. J. Paul. Low loss Ge-on-Si waveguides operating in the 8–14  μm atmospheric transmission window. Opt. Express, 26, 25667-25675(2018).

[26] W. Li, P. Anantha, S. Bao, K. H. Lee, X. Guo, T. Hu, L. Zhang, H. Wang, R. Soref, C. S. Tan. Germanium-on-silicon nitride waveguides for mid-infrared integrated photonics. Appl. Phys. Lett., 109, 241101(2016).

[27] A. Osman, M. Nedeljkovic, J. Soler Penades, Y. Wu, Z. Qu, A. Z. Khokhar, K. Debnath, G. Z. Mashanovich. Suspended low-loss germanium waveguides for the longwave infrared. Opt. Lett., 43, 5997-6000(2018).

[28] D. Ren, C. Dong, S. J. Addamane, D. Burghoff. High-quality microresonators in the longwave infrared based on native germanium. Nat. Commun., 13, 5727(2022).

[29] J. Lim, J. Shim, I. Kim, S. K. Kim, H. Lim, S.-Y. Ahn, J. Park, D.-M. Geum, S. H. Kim. Low-loss and high-confinement photonic platform based on germanium-on-insulator at mid-infrared range for optical sensing. J. Lightwave Technol., 41, 2824-2833(2023).

[30] S. H. Kim, J.-H. Han, J.-P. Shim, H.-J. Kim, W. J. Choi. Verification of Ge-on-insulator structure for a mid-infrared photonics platform. Opt. Mater. Express, 8, 440-451(2018).

[31] S. H. Kim, D.-M. Geum, M.-S. Park, W. J. Choi. In_0.53Ga_0.47As-on-insulator metal–oxide–semiconductor field-effect transistors utilizing Y₂O₃ buried oxide. IEEE Electron Device Lett., 36, 451-453(2015).

[32] A. Li, T. Van Vaerenbergh, P. De Heyn, P. Bienstman, W. Bogaerts. Backscattering in silicon microring resonators: a quantitative analysis. Laser Photon. Rev., 10, 420-431(2016).

[33] P. E. Barclay, K. Srinivasan, O. Painter. Nonlinear response of silicon photonic crystal microresonators excited via an integrated waveguide and fiber taper. Opt. Express, 13, 801-820(2005).

[34] X. Jiang, H. Wu, D. Dai. Low-loss and low-crosstalk multimode waveguide bend on silicon. Opt. Express, 26, 17680-17689(2018).

[35] G. Moille, Q. Li, T. C. Briles, S.-P. Yu, T. Drake, X. Lu, A. Rao, D. Westly, S. B. Papp, K. Srinivasan. Broadband resonator-waveguide coupling for efficient extraction of octave-spanning microcombs. Opt. Lett., 44, 4737-4740(2019).

[36] H.-T. Kim, M. Yu. Cascaded ring resonator-based temperature sensor with simultaneously enhanced sensitivity and range. Opt. Express, 24, 9501-9510(2016).

[37] T.-H. Xiao, Z. Zhao, W. Zhou, C.-Y. Chang, S. Y. Set, M. Takenaka, H. K. Tsang, Z. Cheng, K. Goda. Mid-infrared high-Q germanium microring resonator. Opt. Lett., 43, 2885-2888(2018).

[38] B. Troia, J. S. Penades, A. Z. Khokhar, M. Nedeljkovic, C. Alonso-Ramos, V. M. Passaro, G. Z. Mashanovich. Germanium-on-silicon Vernier-effect photonic microcavities for the mid-infrared. Opt. Lett., 41, 610-613(2016).

[39] R. Morgan, C. Heidelberger, D. Kharas, K. Cahoy, C. Sorace-Agaskar. Low-loss germanium-on-silicon waveguides and ring resonators for the mid-wave infrared. Technical Digest Series, SW5O.1(2022).

[40] S. Radosavljevic, N. T. Beneitez, A. Katumba, M. Muneeb, M. Vanslembrouck, B. Kuyken, G. Roelkens. Mid-infrared Vernier racetrack resonator tunable filter implemented on a germanium on SOI waveguide platform [invited]. Opt. Mater. Express, 8, 824-835(2018).

[41] D. A. Kozak, N. F. Tyndall, M. W. Pruessner, W. S. Rabinovich, T. H. Stievater. Germanium-on-silicon waveguides for long-wave integrated photonics: ring resonance and thermo-optics. Opt. Express, 29, 15443-15451(2021).

[42] R. Armand, M. Perestjuk, A. D. Torre, M. Sinobad, A. Mitchell, A. Boes, J.-M. Hartmann, J.-M. Fedeli, V. Reboud, P. Brianceau, A. D. Rossi, S. Combrié, C. Monat, C. Grillet. Mid-infrared integrated silicon–germanium ring resonator with high Q-factor. APL Photon., 8, 071301(2023).

[43] J. M. Ramirez, Q. Liu, V. Vakarin, X. Le Roux, J. Frigerio, A. Ballabio, C. Alonso-Ramos, E. T. Simola, L. Vivien, G. Isella, D. Marris-Morini. Broadband integrated racetrack ring resonators for long-wave infrared photonics. Opt. Lett., 44, 407-410(2019).

[44] K. Zhang, G. Böhm, M. A. Belkin. Mid-infrared microring resonators and optical waveguides on an InP platform. Appl. Phys. Lett., 120, 061106(2022).

[45] J. Haas, P. Artmann, B. Mizaikoff. Mid-infrared GaAs/AlGaAs micro-ring resonators characterized via thermal tuning. RSC Adv., 9, 8594-8599(2019).

[46] P. Ma, D.-Y. Choi, Y. Yu, Z. Yang, K. Vu, T. Nguyen, A. Mitchell, B. Luther-Davies, S. Madden. High Q factor chalcogenide ring resonators for cavity-enhanced MIR spectroscopic sensing. Opt. Express, 23, 19969-19979(2015).

[47] Y. Chen, H. Lin, J. Hu, M. Li. Heterogeneously integrated silicon photonics for the mid-infrared and spectroscopic sensing. ACS Nano, 8, 6955-6961(2014).